Performance characteristics of snowmobiles, including ride comfort and weight balance, depend upon a variety of systems and components, including the snowmobile suspension. Modern snowmobile suspensions typically include two systems, a front suspension system for the skis and a rear suspension system for the track.
The rear suspension of a snowmobile supports an endless track driven by the snowmobile engine to propel the machine. The track is supported beneath the vehicle chassis by a suspension that is designed to provide proper weight balance and ride comfort by absorbing some of shock as the snowmobile traverses uneven terrain. Most modern snowmobiles utilize a slide rail suspension which incorporates a slide rail along with several idler wheels to support the track. The slide rail typically is suspended beneath the chassis by two or more suspension arms, each arm being attached at its upper end to the chassis of the snowmobile and attached at its lower end to the slide rail. The mechanical linkage of the slide rail to the suspension arms and to the snowmobile chassis typically is provided with springs and one or more shock absorbers, the springs being loaded to urge the slide rails downwardly away from the snowmobile chassis, and the shocks providing dampening forces for improved ride comfort.
A variety of configurations of suspension arms, springs, shocks, and shock rods have been utilized to alter the characteristics and feel of the ride given by a particular suspension system. U.S. Pat. No. 5,265,692 shows a snowmobile track suspension having a pair of generally parallel suspension arms connecting the slide rail to the snowmobile chassis. The lower end of the rear suspension arm has a pivot mount that is movable longitudinally of the slide rail. When this pivot is located at its forward most portion of longitudinal movement (i.e., at the forward end of a longitudinal slot), the suspension arms form a parallelogram with the snowmobile chassis and the slide rail so that upward movement of the front suspension arm is transmitted through the slide rail to the rear suspension arm, causing the slide rail to move upward in an orientation that is generally parallel to the snowmobile chassis. Thus, the front end of the slide rail cannot move higher than the back end of the slide rail. The longitudinal slot into which the lower end of the rear suspension arm is pivotally mounted permits the back end of these slide rails to move higher than the front end of the rails.
In light of the varying characteristics that can be built into a suspension system, a variety of competing suspension systems have been made commercially available, and different types of suspension systems commonly are employed on different types of machines, depending upon their primary usage (e.g., racing, touring, etc.). A need remains for an adjustable suspension system adaptable to perform across a variety of terrain and under diverse conditions.